1. Field of the Invention
The present invention relates to antenna alignment systems and, more particularly, but not by way of limitation, to a device for aligning an antenna by the combination of initial adjustment and selectively staged, controlled movement thereof preparatory to a secondary adjustment.
2. History of Related Art
The importance of accurately aligning a communication antenna relative to the associated signal source with which the antenna is positioned to communicate is well known. Such alignment is necessary for both land based and satellite based signal transmission systems. In either installation, it is important that the antenna be aligned along at least two axes. The first axis is that of the horizontal orientation of the antenna, or azimuth, and the second axis is that of the vertical orientation or elevation. Other antenna alignment aspects include the hour angle axis and the like, as set forth in U.S. Pat. No. 4,232,320 assigned to assignee of the present invention. As set forth in the ""320 Patent, it is well established that the ability to assemble, mount and align an antenna with the fewest manual adjustments and the most efficiency is of great advantage. The requisite mounting assembly necessary for such alignment is, however, a matter of constant design emphasis.
As set forth above, the precise alignment of antennas is a critical function. In order to facilitate alignment, electronic devices such as those that measure the strength of the signal to the antenna have been designed for use during the antenna installation. It is, however, necessary that the antenna be generally aligned with its designated signal source, such as a satellite, before such electronic devices that measure the strength of the signal to the antenna can be utilized. A coarse alignment of the antenna is thus necessary in order to first obtain a signal for subsequent dual axis tuning of the antenna""s azimuthal and elevational orientations.
It is also well known that the proper installation of an antenna is dependent upon an appropriate mounting platform, or base, and associated mounting hardware for use therewith. The stability of the base and the reliability of the mounting hardware are critical to a proper installation. The reliable and efficient mounting of the antenna is also dependent upon a viable method of and apparatus for aligning both azimuthal and elevational orientations accommodating both environmental and expense issues. Such antenna alignment must, however, provide a reliable positioning of the antenna about the above-referenced axes while affording ease in the ultimate securement of the antenna about the mounting base.
Ultimate securement of an antenna necessitates a primary alignment system that does not manifest backlash and/or other relative movement between parts that results in secondary misalignment of the antenna. Primary alignment occurs when the antenna is being oriented and precisely positioned relative to detected antenna signal strength. Once this determination of precise alignment has been determined, secondary misalignment can be caused by a variety of reasons including improperly designed systems, incorrectly assembled hardware, and/or loose connections between mounting members. Any degree of relative movement between mounting or alignment members, such as the above-referenced backlash, can result in secondary misalignment. It has been noted that much secondary misalignment of antennas during installation is the result of backlash, which itself has been a subject of a number of prior designs for antenna alignment devices. For example, U.S. Pat. No. 5,245,351 discloses an orientation adjusting device for a satellite transmitting antenna incorporating an electromechanical actuation system. In this particular example, the system is built into the antenna mounting assembly. The inclusion of such an electromechanical system is not always feasible. Notwithstanding this fact, the system of the ""351 Patent incorporates a gear pivotally fixed on the housing and biased so as to maintain a more precise engagement to reduce the backlash normally associated with a gear drive. The biasing of the gear drive then provides the inherent accuracy and stability for antenna alignment necessarily maintained for the system is to operate correctly.
Although electromechanical systems can be utilized for the orientation and adjustment for a given satellite antenna or the like, such systems are inherently expensive and generally require a power source and maintenance. Certain antenna installations are of the nature that an initial alignment must be manually performed during installation with the antenna subsequently secured in that precise alignment. Such installations require appropriate mechanical mounting systems, including base, couplings, clamps and strut assemblies and other devices that facilitate the direction for and desired degree of antenna movement for the orientation of the antenna. For example, U.S. Pat. No. 5,977,922 teaches a satellite antenna alignment device that is temporarily mounted to a support arm of the antenna to indicate the directional position. Other apparatus and systems are used to impart precise movement to the antenna for alignment purposes as well as the subsequent securement of the requisite mounting members for maintaining that alignment. Since the antenna must generally be aligned along at least two orthogonal axes, such mounting and coupling systems may be mechanically complex in that they are critical to efficient installations.
The present invention provides such an advance over existing mounting systems by utilizing an alignment mechanism capable of being demountably coupled to the antenna mounting structure for precisely aligning and tuning that structure and the associated antenna to obtain a true peak signal when using electronic testing equipment therewith. This operation is facilitated by the tool affording two separate degrees of adjustment. The first degree of adjustment allows fine tuning of the antenna""s position after the antenna is panned in during installation. The signal level is then monitored. The tool also provides a tuning step that alternatively allows movement of the antenna in mutually opposite, equal directions to thereby permit a determination of signal level strength variation and the concomitant ability to make further, secondary adjustments with the tool in response thereto.